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?-Selective cross-coupling of allylic silanolate salts with aromatic bromides using trialkylphosphonium tetrafluoroborate salts prepared directly from phosphine•borane adducts.

ABSTRACT: The ?-selective, palladium-catalyzed cross-coupling of sodium (Z)-2-butenyldiethylsilanolate with a variety of aromatic bromides is reported. The protocol provides high yields (73-94%) and site selectivity (?/?, 25:1 ? > 99:1) in the coupling of electron-rich, electron-poor, sterically hindered, and heteroaromatic bromides. The use of a configurationally homogeneous (Z)-silanolate, nontransferable ethyl groups, and a sterically bulky trialkylphosphonium tetrafluoroborate salt (t-BuCy(2)PH(+)BF(4)(-)) prepared directly from the corresponding air-stable phosphine•borane adduct are critical to the success of the method.

SUBMITTER: Denmark SE

PROVIDER: S-EPMC3163020 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature

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γ-Selective cross-coupling of allylic silanolate salts with aromatic bromides using trialkylphosphonium tetrafluoroborate salts prepared directly from phosphine•borane adducts.

Denmark Scott E SE Werner Nathan S NS

Organic letters 20110810 17

The γ-selective, palladium-catalyzed cross-coupling of sodium (Z)-2-butenyldiethylsilanolate with a variety of aromatic bromides is reported. The protocol provides high yields (73-94%) and site selectivity (γ/α, 25:1 → > 99:1) in the coupling of electron-rich, electron-poor, sterically hindered, and heteroaromatic bromides. The use of a configurationally homogeneous (Z)-silanolate, nontransferable ethyl groups, and a sterically bulky trialkylphosphonium tetrafluoroborate salt (t-BuCy(2)PH(+)BF(4 ...[more]

PMID: 21830766

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